Size correlation between the tibial anterior cruciate ligament footprint and the tibia plateau

Current trends in graft choice for anterior cruciate ligament reconstruction - part I: anatomy, biomechanics, graft incorporation and fixation

Graft selection in anterior cruciate ligament (ACL) reconstruction is critical, as it remains one of the most easily adjustable factors affecting graft rupture and reoperation rates. Commonly used autografts, including hamstring tendon, quadriceps tendon and bone-patellar-tendon-bone, are reported to be biomechanically equivalent or superior compared to the native ACL. Despite this, such grafts are unable to perfectly replicate the complex anatomical and histological characteristics of the native ACL. While there remains inconclusive evidence as to the superiority of one autograft in terms of graft incorporation and maturity, allografts appear to demonstrate slower incorporation and maturity compared to autografts. Graft fixation also affects graft properties and subsequent outcomes, with each technique having unique advantages and disadvantages that should be carefully considered during graft selection.

Anatomic anterior cruciate ligament reconstruction: Freddie Fu's paradigm

Anterior cruciate ligament (ACL) reconstruction techniques have evolved over the past four decades. There is evidence that non-anatomic reconstruction techniques, such as traditional transtibial drilling, fail to recreate the native anatomy of the ACL, which can lead to increased rotatory knee instability, revision risk, and post-traumatic osteoarthritis. Anatomic ACL reconstruction has emerged as the gold standard, with the goal of restoring the patient's native anatomy and knee kinematics. This review will summarise the relevant anatomy, modern anatomic ACL reconstruction techniques, and literature supporting anatomic ACL reconstruction as the new paradigm. LEVEL OF EVIDENCE: Level V, review article.

Tibial Spine Location Influences Tibial Tunnel Placement in Anatomical Single-Bundle Anterior Cruciate Ligament Reconstruction

The purpose of this study was to assess the influence of tibial spine location on tibial tunnel placement in anatomical single-bundle anterior cruciate ligament (ACL) reconstruction using three-dimensional computed tomography (3D-CT). A total of 39 patients undergoing anatomical single-bundle ACL reconstruction were included in this study (30 females and 9 males; average age: 29 ± 15.2 years). In anatomical single-bundle ACL reconstruction, the tibial and femoral tunnels were created close to the anteromedial bundle insertion site using a transportal technique. Using postoperative 3D-CT, accurate axial views of the tibia plateau were evaluated. By assuming the medial and anterior borders of the tibia plateau as 0% and the lateral and posterior borders as 100%, the location of the medial and lateral tibial spine, and the center of the tibial tunnel were calculated. Statistical analysis was performed to assess the correlation between tibial spine location and tibial tunnel placement. The medial tibial spine was located at 54.7 ± 4.5% from the anterior border and 41.3 ± 3% from the medial border. The lateral tibial spine was located at 58.7 ± 5.1% from the anterior border and 55.3 ± 2.8% from the medial border. The ACL tibial tunnel was located at 34.8 ± 7.7% from the anterior border and 48.2 ± 3.4% from the medial border. Mediolateral tunnel placement was significantly correlated with medial and lateral tibial spine location. However, for anteroposterior tunnel placement, no significant correlation was found. A significant correlation was observed between mediolateral ACL tibial tunnel placement and medial and lateral tibial spine location. For clinical relevance, tibial ACL tunnel placement might be unintentionally influenced by tibial spine location. Confirmation of the ACL footprint is required to create accurate anatomical tunnels during surgery. This is a Level III; case-control study.

Current trends in the anterior cruciate ligament part 1: biology and biomechanics

A trend within the orthopedic community is rejection of the belief that "one size fits all." Freddie Fu, among others, strived to individualize the treatment of anterior cruciate ligament (ACL) injuries based on the patient's anatomy. Further, during the last two decades, greater emphasis has been placed on improving the outcomes of ACL reconstruction (ACL-R). Accordingly, anatomic tunnel placement is paramount in preventing graft impingement and restoring knee kinematics. Additionally, identification and management of concomitant knee injuries help to re-establish knee kinematics and prevent lower outcomes and registry studies continue to determine which graft yields the best outcomes. The utilization of registry studies has provided several large-scale epidemiologic studies that have bolstered outcomes data, such as avoiding allografts in pediatric populations and incorporating extra-articular stabilizing procedures in younger athletes to prevent re-rupture. In describing the anatomic and biomechanical understanding of the ACL and the resulting improvements in terms of surgical reconstruction, the purpose of this article is to illustrate how basic science advancements have directly led to improvements in clinical outcomes for ACL-injured patients.Level of evidenceV.

The radiographic tibial spine area is correlated with the occurrence of ACL injury

PURPOSE

The purpose of this study was to reveal the possible influence of the tibial spine area on the occurrence of ACL injury.

METHODS

Thirty-nine subjects undergoing anatomical ACL reconstruction (30 female, 9 male: average age 29 ± 15.2) and 37 subjects with intact ACL (21 female, 16 male: average age 29 ± 12.5) were included in this study. In the anterior-posterior (A-P) and lateral knee radiograph, the tibial spine area was measured using a PACS system. In axial knee MRI exhibiting the longest femoral epicondylar length, the intercondylar notch area was measured. Tibial spine area, tibial spine area/body height, and tibial spine area/notch area were compared between the ACL tear and intact groups.

RESULTS

The A-P tibial spine area of the ACL tear and intact groups was 178 ± 34 and 220.7 ± 58mm², respectively. The lateral tibial spine area of the ACL tear and intact groups was 145.7 ± 36.9 and 178.9 ± 41.7mm², respectively. The tibial spine area was significantly larger in the ACL intact group when compared with the ACL tear group (A-P: p = 0.02, lateral: p = 0.03). This trend was unchanged even when the tibial spine area was normalized by body height (A-P: p = 0.01, lateral: p = 0.02). The tibial spine area/notch area of the ACL tear and intact groups showed no significant difference.

CONCLUSION

The A-P and lateral tibial spine area was significantly smaller in the ACL tear group when compared with the ACL intact group. Although the sample size was limited, a small tibial spine might be a cause of knee instability, which may result in ACL injury.

LEVEL OF EVIDENCE

Level III.

Truncated-pyramid shape simulation for the measurement of femoral intercondylar notch volume can detect the volume difference between ACL-injured and intact subjects

PURPOSE

The purpose of this study was to measure the femoral intercondylar notch volume using a truncated-pyramid shape simulation and compare this volume between anterior cruciate ligament (ACL) injured and intact subjects.

METHODS

Forty-seven subjects diagnosed with ACL tear by MRI (22 male and 25 female: median age 26: range 15-49), and 41 subjects in which knee MRI was performed and no ACL injury detected (20 males and 21 females: median age 27: range 16-49), were included in this study. Using three-dimensional computed tomography (3D-CT), the axial femoral intercondylar notch area was measured in the slice containing the most proximal (S1) and most distal (S2) level of Blumensaat's line. Femoral condyle height (h) was measured using a sagittal view of knees in 3D-CT. The truncated-pyramid shape simulation was calculated as: Volume = [Formula: see text]. Statistical analysis was performed to compare S1, S2, notch height, and notch volume between the ACL-injured and intact groups.

RESULTS

The measured S1, S2, and the notch height of the ACL-injured and intact groups were 201 ± 64 and 214 ± 50mm², 370 ± 91 and 461 ± 94mm², and 31 ± 3 and 30 ± 4mm, respectively. The calculated femoral intercondylar notch volume of the ACL-injured and intact groups was 8.6 ± 2.2 and 9.9 ± 2.6cm³, respectively. The ACL intact group showed significantly larger S2 and notch volume when compared with the ACL-injured group.

CONCLUSION

For clinical relevance, notch volume and most distal axial notch area parameters were significantly larger in ACL intact subjects. The truncated-pyramid shape simulation is an easy and cost-effective method to evaluate intercondylar notch volume. In knees with small femoral intercondylar notch volume, attention is needed to prevent ACL injury.

LEVEL OF EVIDENCE

Level III.

Enlarged tibial eminence may be a protective factor of anterior cruciate ligament

Anterior cruciate ligament (ACL) is a primary stabilizer of the knee and constrains joint motion, and its injury is very common in clinic. There are many studies on the risk factors of ACL injury such as the ACL diameter, intercondylar notch width index (NWI), sagittal condylar shape, tibial posterior slope, tibia eminence size and so on. Large amount of research data has confirmed that all above are closely related to ACL injury. Among them the morphological characteristics of femoral condyle and tibial plateau are closely related to ACL injury. For example the tibial eminence, which is the hot topic of recent research. Whether or how does it relate to ACL injury has draw much interest of researchers. Since the tibial eminence and the ACL are both located in the intercondylar notch and adjacent to each other, we hypothesize the size of the tibial eminence may relate to the rupture of ACL. For there is report have found that reduced medial tibial eminence was associated with ACL injury, we suggest a hypothesis that enlarged tibia eminence may be a protective factor of ACL.

The occurrence of ACL injury influenced by the variance in width between the tibial spine and the femoral intercondylar notch

PURPOSE

The purpose of this study was to reveal the influence of the variance in width between the tibial spine and the femoral intercondylar notch on the occurrence of ACL injury.

METHODS

Thirty-nine subjects undergoing anatomical ACL reconstruction (30 female, 9 male; average age 29 ± 15.2) and 37 subjects with intact ACL (21 female, 16 male; average age 29 ± 12.5) were included in this study. In the anterior-posterior knee radiograph, tibial spine height, and the length between the top of the medial and lateral tibial spine (tibial spine width) were measured. In axial knee MRI exhibiting the longest femoral epicondylar length, intercondylar notch outlet length was measured and notch width index was calculated. Tibial spine width/notch outlet length, and tibial spine width/notch width index were compared between the ACL tear and intact groups.

RESULTS

Tibial spine width/notch outlet length of the ACL tear and intact groups was 0.6 ± 0.1 and 0.7 ± 0.1, respectively. Tibial spine width/notch width index of the ACL tear and intact groups was 0.4 ± 0.1, and 0.6 ± 0.1, respectively. Both parameters were significantly larger in the ACL intact group.

CONCLUSION

Both tibial spine width/notch outlet length and tibial spine width/notch width index were significantly smaller in the ACL tear group when compared with the ACL intact group. The occurrence of ACL injury influenced by the variance in width between the tibial spine and the femoral intercondylar notch.

LEVEL OF EVIDENCE

III.

Size and Shape of the Human Anterior Cruciate Ligament and the Impact of Sex and Skeletal Growth: A Systematic Review

BACKGROUND

High rates of anterior cruciate ligament (ACL) injury and surgical reconstruction in both skeletally immature and mature populations have led to many studies investigating the size and shape of the healthy ligament. The purposes of the present study were to compile existing quantitative measurements of the geometry of the ACL, its bundles, and its insertion sites and to describe effects of common covariates such as sex and age.

METHODS

A search of the Web of Science was conducted for studies published from January 1, 1900, to April 11, 2018, describing length, cross-sectional area, volume, orientation, and insertion sites of the ACL. Two reviewers independently screened and reviewed the articles to collect quantitative data for each parameter.

RESULTS

Quantitative data were collected from 92 articles in this systematic review. In studies of adults, reports of average ACL length, cross-sectional area, and volume ranged from 26 to 38 mm, 30 to 53 mm, and 854 to 1,858 mm, respectively. Reported values were commonly found to vary according to sex and skeletal maturity as well as measurement technique.

CONCLUSIONS

Although the geometry of the ACL has been described widely in the literature, quantitative measurements can depend on sex, age, and measurement modality, contributing to variability between studies. As such, care must be taken to account for these factors. The present study condenses measurements describing the geometry of the ACL, its individual bundles, and its insertion sites, accounting for common covariates when possible, to provide a resource to the clinical and scientific communities.

CLINICAL RELEVANCE

Quantitative measures of ACL geometry are informative for developing clinical treatments such as ACL reconstruction. Age and sex can impact these parameters.

Anatomical relationship between insertion sites, tunnel placement, and lateral meniscus anterior horn injury during single and double bundle anterior cruciate ligament reconstructions: A comparative macroscopic and histopathological evaluation in cadavers

PURPOSE

The influence of tunnel extension outside the anatomical anterior cruciate ligament (ACL) insertion in single-bundle (SB) or double-bundle (DB) ACL reconstruction is unclear. This study aimed to investigate the anatomical relationship between ACL insertion and tunnel extension in SB and DB ACL reconstruction, and the impact of tibial tunnel extension to the insertion of anterior horn of lateral meniscus in terms of injury.

METHODS

Forty-six paired cadaver knees (mean age, 82.7 ± 10.7 years) were used. Right and left knees were used for SB (10 mm) and DB tunnel reaming (6 mm for the anteromedial and posterolateral bundles). Tibial and femoral tunnels were created to aim at the center of the ACL insertion by arthroscopic visualization. The relationship between tunnel extension and ACL insertion was evaluated macroscopically, and there ratio in two groups were compared by chi-square test. Further, the relative risk for meniscus injury based on tunnel placement was estimated. Coronal section of tibia and parallel section to Blumensaat line in femur were prepared to evaluate the relationship among tunnel position, ACL insertion, and anterior horn of the meniscus histologically.

RESULTS

Tibial tunnel extension out of the ACL insertion was observed macroscopically in 9 (39.1%) knees of the SB group, and 3 (13.0%) of the DB group (p = 0.045). In femoral tunnels, extension out of the ACL insertion was seen in 8 (34.8%) knees of the SB group and 1 (4.3%) of the DB group (p = 0.011). Partial injuries of the lateral meniscus anterior horn (LMAH) were observed in 5 (21.7%) knees of the SB group and 1 (4.3%) knee of the DB group (p = 0.091). The relative risk for LMAH injury was calculated as 5.0 (odds ratio, 6.1). Microscopically, SB tunnels appeared to expand out of ACL insertion, both in the femur and tibia.

CONCLUSIONS

The incidence of tunnel extension out of the ACL insertion in femur and tibia were higher with SB than with DB reconstruction. Furthermore, injury rate of the LMAH in the DB group was lower.

Individualized Anterior Cruciate Ligament Graft Matching: In Vivo Comparison of Cross-sectional Areas of Hamstring, Patellar, and Quadriceps Tendon Grafts and ACL Insertion Area

BACKGROUND

Recent literature correlated anterior cruciate ligament (ACL) reconstruction failure to smaller diameter of the harvested hamstring (HS) autograft. However, this approach may be a simplification, as relation of graft size to native ACL size is not typically assessed and oversized grafts may impart their own complications.

PURPOSE

To evaluate in vivo data to determine if the commonly used autografts reliably restore native ACL size.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Intraoperative data of the tibial insertion area and HS graft diameter were collected and retrospectively evaluated for 46 patients who underwent ACL reconstruction with HS autografts. Magnetic resonance imaging measurements of the cross-sectional area (CSA) of the possible patellar tendon (PT) and quadriceps tendon (QT) autografts were also done for each patient. The percentages of tibial insertion site area restored by the 3 possible grafts were then calculated and compared for each individual.

RESULTS

The mean ACL tibial insertion area was 107.2 mm² (60.5-155.5 mm²). The mean CSAs of PT, HS, and QT were 33.2, 55.3, and 71.4 mm², respectively. When all grafts were evaluated, the percentage reconstruction of the insertion area varied from 16.2% to 123.1% on the tibial site and from 25.5% to 176.7% on the femoral site, differing significantly for each graft type ( P < .05). On average, 32.8% of the tibial insertion area would have been filled with PT, 53.6% by HS, and 69.5% by QT. Based on previous cadaveric studies indicating that graft size goal should be 50.2% ± 15% of the tibial insertion area, 82.7% of patients in the HS group were within this range (36.9%, QT; 30.5%, PT), while 65.2% in the PT group were below it and 60.9% in the QT group were above it.

CONCLUSION

ACL insertion size and the CSAs of 3 commonly used grafts vary greatly for each patient and are not correlated with one another. Thus, if the reconstructed ACL size is determined by the harvested autograft size alone, native ACL size may not be adequately restored. PT grafts tended to undersize the native ACL, while QT might oversize it.

CLINICAL RELEVANCE

These results may help surgeons in preoperative planning, as magnetic resonance imaging measurements can be helpful in determining individualized graft choice to adequately restore the native ACL.

A Comparison Between Chinese and Caucasian 3-Dimensional Bony Morphometry in Presimulated and Postsimulated Osteotomy for Total Knee Arthroplasty

BACKGROUND

The bone morphologies of intact knees were measured and compared between Chinese and Caucasian populations. However, to assess if distinct designs of implants are necessary for the Chinese population owing to different morphologies and sizes, the knee measurements after osteotomy performed in total knee arthroplasty were evaluated.

METHODS

Thirty-seven Caucasian and 50 Chinese patients' knees were examined using computed tomography scans. Mimics were applied to reconstruct 3-dimensional bone models. Dimensions of the 3-dimensional knee models and simulated bone resections during total knee arthroplasty were measured using Geomagic Studio and Pro/ENGINEER. The morphologic measurements of the native and resected femur and tibia included the anteroposterior (AP) depth, mediolateral (ML) width, notch width, knee physical valgus angle, tibial slope angle, and the ML-to-AP ratio of the femur, tibia, and resected femur. Statistical analysis was performed using the independent samples t test and the Pearson correlation coefficient in SPSS for Windows. Values of P < .05 were considered significant.

RESULTS

No measurements were significantly different between the Chinese and Caucasian knees. However, the Chinese female showed significant differences compared with the Chinese male on distal femoral measurements both presimulated and postsimulated osteotomy such as a smaller mean ML-to-AP ratio in presimulated (1.3 ± 0.1) and postsimulated (1.3 ± 0.1) osteotomy.

CONCLUSION

The necessity of designing a full set of total knee components specifically for the Chinese population is still undetermined. However, we suggest designing femoral components specific for the Chinese females because of different postosteotomy distal femoral ML-to-AP ratio between the Chinese males and the Chinese females.

Variation in the shape of the tibial insertion site of the anterior cruciate ligament: classification is required

PURPOSE

To propose a classification system for the shape of the tibial insertion site (TIS) of the anterior cruciate ligament (ACL) and to demonstrate the intra- and inter-rater agreement of this system. Due to variation in shape and size, different surgical approaches may be feasible to improve reconstruction of the TIS.

METHODS

One hundred patients with a mean age of 26 ± 11 years were included. The ACL was cut arthroscopically at the base of the tibial insertion site. Arthroscopic images were taken from the lateral and medial portal. Images were de-identified and duplicated. Two blinded observers classified the tibial insertion site according to a classification system.

RESULTS

The tibial insertion site was classified as type I (elliptical) in 51 knees (51 %), type II (triangular) in 33 knees (33 %) and type III (C-shaped) in 16 knees (16 %). There was good agreement between raters when viewing the insertion site from the lateral portal (κ = 0.65) as well as from the medial portal (κ = 0.66). Intra-rater reliability was good to excellent. Agreement in the description of the insertion site between the medial and lateral portals was good for rater 1 and good for rater 2 (κ = 0.74 and 0.77, respectively).

CONCLUSION

There is variation in the shape of the ACL TIS. The classification system is a repeatable and reliable tool to summarize the shape of the TIS using three common patterns. For clinical relevance, different shapes may require different types of reconstruction to ensure proper footprint restoration. Consideration of the individual TIS shape is required to prevent iatrogenic damage of adjacent structures like the menisci.

LEVEL OF EVIDENCE

III.

Radiographic femoral bicondylar width predicts anterior cruciate ligament insertion site sizes

PURPOSE

The purpose of this study was to determine whether radiographic femoral bicondylar width predicts intra-operative anterior cruciate ligament (ACL) insertion site sizes.

METHODS

Seventy-three consecutive patients (39 males and 34 females; mean age 25.2 years ± 10.2) who underwent anatomic ACL reconstruction were retrospectively reviewed. Femoral condyle width was measured using a pre-operative anteroposterior (AP) radiograph of the operative knee. Lines were drawn through the anatomic axis of the femur, as well as perpendicularly through the condyles. Bicondylar width was measured as the maximum width across both the medial and lateral femoral condyles utilizing this perpendicular line. The ACL insertion site lengths (in the AP direction) of both the tibia and the femur were measured intra-operatively using a commercially available arthroscopic ruler.

RESULTS

The average bicondylar width was significantly smaller for females compared to males (p < 0.05). The average tibial and femoral insertion site sizes were significantly smaller for females compared to males (p < 0.05). Regression analysis predicted tibial (r ² = 0.88) and femoral (r ² = 0.90) insertion site sizes based on femoral bicondylar width measurements.

CONCLUSION

A simple radiographic measurement of femoral bicondylar width can predict intra-operative tibial and femoral insertion site sizes, which has the potential to assist surgeons in performing individualized ACL reconstruction in cases where MRI scan is unavailable.

LEVEL OF EVIDENCE

IV.

Area of the tibial insertion site of the anterior cruciate ligament as a predictor for graft size

PURPOSE

To determine the distribution of different sizes of the area of the tibial insertion site among the population and to evaluate whether preoperative MRI measurements correlate with intraoperative findings to enable preoperative planning of the required graft size to cover the tibial insertion site sufficiently. The hypothesis was that the area of the tibial insertion site varies among individuals and that there is good agreement between MRI and intraoperative measurements.

METHODS

Intraoperative measurements of the tibial insertion site were taken on 117 patients. Three measurements were taken in each plane building a grid to cover the tibial insertion site as closely as possible. The mean of the three measurements in each plane was used for determination of the area. Two orthopaedic surgeons, who were blinded to the intraoperative measurements, took magnetic resonance imaging (MRI) measurements of the area of the tibial insertion site at two different time points.

RESULTS

The intraoperative measured mean area was 123.8 ± 21.5 mm². The mean area was 132.8 ± 15.7 mm² (rater 1) and 136.7 ± 15.4 mm² (rater 2) when determined using MRI. The size of the area was approximately normally distributed. Inter-rater (0.89; 95 % CI 0.84, 0.92; p < 0.001) and intrarater reliability (rater 1: 0.97; 95 % CI 0.95, 0.98; p < 0.001; rater 2: 0.95; 95 % CI 0.92, 0.96; p < 0.001) demonstrated excellent test-retest reliability. There was good agreement between MRI and intraoperative measurement of tibial insertion site area (ICCs rater 1: 0.80; 95 % CI 0.71, 0.87; p < 0.001; rater 2: 0.87; 95 % CI 0.81, 0.91; p < 0.001).

CONCLUSION

The tibial insertion site varies in size and shape. Preoperative determination of the area using MRI is repeatable and enables planning of graft choice and size to optimally cover the tibial insertion site.

LEVEL OF EVIDENCE

III.

Anatomic ACL reconstruction: the normal central tibial footprint position and a standardised technique for measuring tibial tunnel location on 3D CT

PURPOSE

The aim of this study was to define the normal ACL central tibial footprint position and describe a standardised technique of measuring tibial tunnel location on 3D CT for anatomic single-bundle ACL reconstruction.

METHODS

The central position of the ACL tibial attachment site was determined on 76 MRI scans of young individuals. The central footprint position was referenced in the anterior-posterior (A-P) and medial-lateral (M-L) planes on a grid system over the widest portion of the proximal tibia. 3D CT images of 26 young individuals had a simulated tibial tunnel centred within the bony landmarks of the ACL footprint, and the same grid system was applied over the widest portion of the proximal tibia. The MRI central footprint position was compared to the 3D CT central footprint position to validate the technique and results.

RESULTS

The median age of the 76 MRI subjects was 24 years, with 32 females and 44 males. The ACL central footprint position was at 39 (±3 %) and 48 (±2 %), in the A-P and M-L planes, respectively. There was no significant difference in this position between sexes. The median age of the 26 CT subjects was 25.5 years, with 10 females and 16 males. The central position of the bony ACL footprint was at 38 (±2 %) and 48 (±2 %), in the A-P and M-L planes, respectively. The MRI and CT central footprint positions were not significantly different in relation to the medial position, but were different in relation to the anterior position (A-P 39 % vs. 38 %, p = 0.01). The absolute difference between the central MRI and CT reference positions was 0.45 mm.

CONCLUSIONS

The ACL's normal central tibial footprint reference position has been defined, and the technique of measuring tibial tunnel location with a standardised grid system is described. This study will assist surgeons in evaluating tibial tunnel position in anatomic single-bundle ACL reconstruction.

LEVEL OF EVIDENCE

III.

Is the femoral lateral condyle's bone morphology the trochlea of the ACL?

PURPOSE

The purpose of this study was to investigate the association of different osteoarticular femoral and tibial morphology and morphometric parameters with the risk of anterior cruciate ligament (ACL) rupture.

METHODS

Thirty-six patients (29 male and 7 female) with an ACL rupture (<6 months) and 36 age and sex-matched controls were included. The anatomomorphological parameters and morphometrics of the distal epiphysis of the femur and proximal epiphysis of the tibia were measured through conventional lateral radiography of the knee.

RESULTS

It was found statistically significant smaller heights of femur's lateral condyle, AP distances of the tibial plateaus and smaller XY and WX distances, as well as, higher XY/AB and B/AB ratios (p < 0.05). In turn, women had smaller AP distances of the femur's lateral condyle, AP distances of the femur's diaphysis, AP distances of the tibial plateaus and heights of femur's lateral condyle, as well as, higher values of XY/AB (Porto ratio) and B/AB ratios (p < 0.05).

CONCLUSIONS

Several femoral and tibial bone morphological parameters were identified as potential risk factors for sustaining an ACL injury. These parameters are clinically relevant to identify individuals with higher risk of ACL injury, decide between conservative or surgical treatment and identify individuals who may benefit from preventive neuromuscular programs.

LEVEL OF EVIDENCE

Case-control study, Level III.

Proportional evaluation of anterior cruciate ligament footprint size and knee bony morphology

PURPOSE

The purpose of this study was to reveal the correlation in size between the native anterior cruciate ligament (ACL) footprint and the femoral intercondylar notch and the tibia plateau, and to calculate the proportion in size between the ACL footprint and knee bony morphology.

METHODS

Twenty-six non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ACL. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on both the femoral and tibial sides. An accurate lateral view of the femoral condyle and an axial view of the tibial plateau were photographed with a digital camera, and the images were downloaded to a personal computer. The size of the femoral and tibial ACL footprints and the area of the lateral wall of the intercondylar notch and the tibia plateau were measured with Image J software (National Institution of Health).

RESULTS

The sizes of the native femoral and tibial ACL footprints were 69.8 ± 25 and 133.8 ± 31.3 mm(2), respectively. The areas of the lateral wall of the intercondylar notch and the tibia plateau were 390.5 ± 70.5 and 2,281.7 ± 377.3 mm(2), respectively. The femoral ACL footprint area and the area of the lateral wall of the femoral intercondylar notch (Pearson's correlation coefficient = 0.603, p = 0.001), and the tibial ACL footprint area and the area of the tibia plateau (Pearson's correlation coefficient = 0.452, p = 0.02) both showed significant correlation. The femoral ACL footprint was 17.8 ± 4.9 %, the size of the lateral wall of the femoral intercondylar notch, and the tibial ACL footprint was 5.9 ± 1.3 %, the size of the tibia plateau.

CONCLUSION

For clinical relevance, the femoral ACL footprint is approximately 18 %, the size of the intercondylar notch, and the tibial ACL footprint is approximately 6 %, the size of the tibia plateau. It might be possible to predict the size of the ACL measuring these parameters preoperatively.

Validation of a method for combining biplanar radiography and magnetic resonance imaging to estimate knee cartilage contact

Combining accurate bone kinematics data from biplane radiography with cartilage models from magnetic resonance imaging, it is possible to estimate tibiofemoral cartilage contact area and centroid location. Proper validation of such estimates, however, has not been performed under loading conditions approximating functional tasks, such as gait, squatting, and stair descent. The goal of this study was to perform an in vitro validation to resolve the accuracy of cartilage contact estimations in comparison to a laser scanning gold standard. Results demonstrated acceptable reliability and accuracy for both contact area and centroid location estimates. Root mean square errors in contact area averaged 8.4% and 4.4% of the medial and lateral compartmental areas, respectively. Modified Sorensen-Dice agreement scores of contact regions averaged 0.81 ± 0.07 for medial and 0.83 ± 0.07 for lateral compartments. These validated methods have applications for in vivo assessment of a variety of patient populations and physical activities, and may lead to greater understanding of the relationships between knee cartilage function, effects of joint injury and treatment, and the development of osteoarthritis.